Electric safety lamp for miners



Dec. 18, 1928. 1,695,794

'0. BECKER, JR

ELECTRIC SAFETY LAMP FOR MINERS Filed April 28, 1927 3 9 I a f 9911A??? Q v 15 Jm'enlorz Olib Becker, 7t.

y Rt forngy Patented Dec. 18, 1928.

UNITED STATES I 1,595,294 PATENT ()FFECE,

OTTO BECKER, an, on BARMEN, GERMANY.

. Application filed April 2s, 1927, Serial No.

candescent lamp which is held in the closed position owing to the pressure existing in the protecting hood. The lamp which forms the subject matter of the present invention differs from the known miners lamps of this kind in which the protecting hood consists of a glasslglobe, in the first place, in that the protecting hood for the incandescent lamp is formed by a metal case, which is advantageously made in one piece with the casing in which the lamp is carried, and a glass front which is removably fitted thereto. By this means it is possible,on the one hand, to make the wall of the pro tecting hood thinner and lighter than heretofore. On the other hand only the glass front'is exposed to the danger. of breakage or damage by splinters of stone. It can, however, in contra-distinction to the complete glass globes hitherto employed, beelfectively protected by means of wire netting or the like fastened to a forwardly projecting edge of the metal case so that damage cannot occur so easily. 'Further, the disadvantage, which exists in the previously known lamps this kind, namely that if a crack in the glass occurs the entire protecting hood can be .used to burst owing to the pressure ting within it whereby people are easily .ngered by flying pieces of glass, is

avoided. Elie new lamp, on the other hand,

can be used, even when the glass front of the protecting hood is cracked, so long as the lack of air-tightness is not so great that, owing to the escape of air, the tall in pressure which occurs in the protecting hood is so eat to cause-the disconnection of the circuit 0? the incandescent lamp. At the same time the air escaping through the places which are not air-tight prevents the access of any outer air, which may be explosive, owingto its being mixed with firedamp or coal-dust. i

Finally, a special advantage which results from constructing the protecting hood from a metal case and a glass front is that, it is sible to conduct the compressed air capes when the glass front is dam ELECTRIC SAFETY LAMP FOR MINER/S.

187,202, and in GermanyNovember 4, 1925.

aged or broken in such a mannerthat the outer air cannot reach the filament of the incandescent lamp, which is generallyalso broken when the glass front 1s broken, be fore the c rcuit breaking switch has switched it off. This can be effected, in accordance with the invention, by arranging the reflector of the incandescent lamp so as to cut off the rear portion of the space within the pro tecting hood containing the inlet opening for the compressedair from the-front portion of the hood'containing'the lamp in such a manner that the two spaces are only in connection the one with the other by means of .an annular gap whichis approximately concentric with the lamp. The result of this arrangement is that, when the glass front is damaged or broken, the air can only escape in a stream ofannular cross-section which envelope the lamp, whereby the in,- candescent lamp is screened from theouter air.

In order to maintain the pressure acting on the walls ofthe protecting hood as small as possible and consequently to be able to make the hood as light as possible, the controlling pressure in the hood is advantageously obtained not, as in. some known types of miners lamps, byfc'onducting fresh compressed air into the hood, but, in a manner also known per so, by conducting the, exhaust air from the motor into the hood and at the same time throttling down the exhaust air at its outlet into the atmosphere. Whereas, in the known. lamps having an arrangement of thisnature, the exhaust air from the motor flows into the' atmosphere at the rear end of the casing and the hood is only connected with the casing of the motor in such a manner that the pressure of thethrottled eXhaust air is transmitted to the hood, in the lamp in accordance with the invention the exhaust air from the motor, and preferably the whole of the exhaust air, isIconducted rightthrough the protecting hood which is provided. with an outlet opening leading into the atmosphere. This ensures that, the con'ipressed air escapes owing to a crack occuring in the glass front or owing to lack of air-tightness produced by other causes, suflicient exhaust air always flows .case 5 the lamp from the access of outer air until it has been completely extinguished.

With the above described arrangement, in which the exhaust air from the motor which drives the current generator is conducted right through the protecting hood of the lamp and is throttled down at its outlet press the contacts of the switch together so that a good connection is made while the device can also be made so sensitive that the switch is opened. even when a relatively small fall of pressure occurs in the protecting hood. This result is obtained, in accordance with the invention, by throttling the exhaust air which flows into the atmosphere by means of a movable throttling disc which is connected with the switch for breaking the circuit in such a manner that theswitch is held closed against the action of an opening spring by means of the pressure exerted by the exhaust air on the throttling disc.

A constructional embodiment of the invention is illustrated by way of example in the accompanying drawing, which shows a longitudinal sectional view of a miners lamp arranged in accordance with the invention.

In the drawing, 1 is a cylindrical metal casing having a fixed wall 2 in front and a removable wall 3 at the back. The rear side of the fixed front wall 2 is provided with a tube-like extension 4, the interior of which is divided into two parts by means of a fixed intermediate wall 4 he front portion of of the tubular extension 4 serves for the reception of the socxet 27 of an incandescent electric lamp 2?, the glass bulb of wh ch containing the filament is in front of the fixed front wall 2. The incandescent lamp 27 is surrounded by a metal case 5 of more or less hopper-like shape which is arranged at the front end of the casing 1 and forms, together with a glass disc 17, a protecting hood for the lamp. The casing 1, front wall 2, tubular extension 4 and. case 5 are preferably cast in one piece as shown in the drawing. The glass disc 17 which closes the secured by means of an internally threaded ring 19, which presses the disc against the edge of the case 5, a packing ring 18 being interposed between the two.

wire net 21, which is fixed to the threaded ring 19, can be arranged in front of the glass disc 17 in order to protect it from possible damage. The rear removable wall 3 of the casing is of hood-like shape and the space within it is shut off from the interior of the casing 1 by means of an intermediate wall 12, which is removably held between the casing 1 and the removable rear wall 3.

The casing 1 contains a current generator which, in order to avoid sliding contacts, consists of several fixed coils 6 and a rotor 7 formed by a permanent magnet. The latter is mountedv on a shaft 8 which is io-urnaled on one side in the rear portion of the tubular extension 4 of the front wall 2 and on the other slde in a hub-l1lie extension 12 in the intermediate wall 12. The rear end of the V ing 15 provided at the edge of the inter-' mediate wall 12 and a longitudinal channel 16 in the casing 1 connected therewith, into the protecting hood 5 of the lamp 2?. From here the air escapes through a special outlet into the atmosphere, being throttled in such a manner that an excess of pressure above the atmospheric pressure exists within the 1 protecting hood 5. This outlet is arranged in the following manner The side of the front wall 2 of the casing which away from the mouth of the channel 16 contains a recess 45, 45 in the form of'a bore of which the rear portion. is reduced and of which the front wider portion 45 contains a box-like chamber 46 which is held in place by a cover 47'which is screwed into an internal thread. provided in the recess 45. The cover 47 has several openings 48 through which the exhaust air can escape from the hood 5 into the chamber 46. That part of the wall of the Cliftl11- ber 46 which is adjacent to the rear end of the chamber contains on the other hand one or more outlet openings 50, which are in connection with the actual exhaust openllll) ing 52 leading to theatinosphere by means of an annular channel 51 surrounding the chamber 46. The exhaust opening 52 is preferably covered, asillustrated, by means of gauze 58 for protection against the ingress of dirt. Further, there also arranged in front of it a guard plate 54 which overlaps the opening, one or more side outlet passages for the air being provided, and prevents the exhaust opening 52 being closed by the hand whereby the operation of the lamp would be interfered with.

A throttling disc 70, the diameter of which is somewhat less than the clear width of thechamber 46, is arranged in the box-like chamber 46 between the cover 4? and the side air outlet openings 50, so that a narrow one hand, of throttling the escaping air trated. in the drawing.

from the hood must flow in order to es cape through the chamber 46,- opening50,v

annular channel'51 and the exhaust outlet 52 into the atmosphere The throttling disc 7 0 is fitted on a rod :71, which is tightly guided in a stuffing-box 55-cast in the rear end ofthe chamber 46," and is movable "to gether with this rod like apiston in the chamber 46. .A spring 56 which surrounds the stuffing-box 55' and the rod 71 always tends to press the rod 71 together with the disc 70 into the forward end position illus- The disc 70'serves the purpose, on the and, on the-other hand, of controlling a circuit breaking switch whichis arranged in the rear narrower portion 45 olf'the'recess 45, 45. fixed contacts 57, 58 arranged at the bot;- tom of the recess and a contactbridge. 59, for connecting the two. The rear ends of these two contacts are formed as terminals and one of them, namely 57, is connected by a conductor 60 with the current generator. The other contact 58 is in connection through a conductor 61 with one of the contacts in-the base of the incandescent lamp 27, the second contact of which is connected by a conductor '62, a, third terminal 63 and a conductor 62' again with the current generator. The contact bridge 59 is fixed to and insulated from the forkedend 71 of the'rod 71 of the disc 70 which rod passes through the bottom of the chamber -46"into the rear portion 45 of the'recess45, 45 The said contact bridge can at the same time swing'about an axis 64 at right angles to the rod 71, so that it can adjust itself automatically to the fixed contacts 57,- 58,

- when pressed against them, in such a manprecious metal, forexample, si'lverForIplatinum,-an d of winch the two limbs are gu1dner that it makes contact {over the full 8X-' tent of the contact surfaces of the fixed contacts. This bridge 59 contains a preliminary contact which: consists of a U-- shaped member or bow 65, which is made of ed in the end portions ofathe bridge, and

which is pressed forwards by means of a spring 66 arranged between the forked head of .the rod 71 and the limbs ofthe bow.

This spring simultaneouslyserves the purpose of normally holding the contact bridge" 59 to the middle position illustrated.

closing the switch, which isefl'ected by-the pressure of the exhaust. air on the disc .70,

the fixed contacts 57, 58'are first connected,

together by the-preliminary contact and only when the circuit. has thus been closed does the bridge itself come torest against the contacts. Conversely,,when the-switch is opened by the spring 56, the bridge 59 This switch consists of twoand contains no opening except that for the passage of the rod 71, so that any spark which may occur on operating the switch remains enelosed in'the chamber in which the switch is contained.

The protecting hood 5 of the incandescent lamp 27 containsa reflector 89, 39*, which, as may be 'seen from the drawing, is trans versely divided into two parts. .Its rear or i-nneriportion 39 is fixed to the fixed front wall volithe casing 2 while the front or outer portion39?- is heldby clamping a collar or flanged edge with which it is provided together with the glass disc 17 and the packing ring 18 between the casing of the hood '5 and the threaded ring 19. Between the two 42. In doing so it forms a current of air of annular'cross-section whichenvelops the lamp 27 and thus prevents the outer air, which may in some cases be explosive, from reaching the filament of the lamp, which may possibly also be broken, and being thereby ignited. Before the pressure in the 1 lamp has become so lowthat the protecting screen of air around the lamp disappears, the lamp circuit is broken by the switch 57,

58, 59 which opens. when the pressure in the hood 5 ,falls' and the 'tinguished.

I he method off-operation of the new lamp is as fol'lows -On opening a cockin the compressed. air inletfconduit, compressed air is admitted to the turbine 11 and the turbine then drives the dynamo 6, 7. The exhaust air from the turbine flows through-the channels 15, 16 into the protectinghood 5 of the incandesfila' nent is thereby excent lamp 27 and thence through the chamber 46, annular channel 51 and 'the exhaust opening 52 into the atmosphere. The air must on its way pass'through the narrow an- 'nular space; between the throttling disc 70 and the wall of the passage formed by the chamber 46'whereby it isthrottled down to such an extent that'an excess of pressureis produced in the hood 5'which. is. snflicienttd incandescent lamp 27 it Cit ' the opening produced by the brealca gives the current oi t'orm at the annular gap 42 in the reflector 39, 89, a screen of air which protects the he glass disc 17 is Owing to the throttling of the exhaust air at the disc 70, the air exerts so great a pressure on this disc in the opposite direction to the pressure of a spring 56 that the disc is pushed inwards. T he contact bridge 59 on the rod 71 is thereby pressed against the fixed contacts 57, 58 and the cirdamaged.

suit of the current generator and the incandescent lamp is thus closed. The incandescent lamp new lights up as long as an excess of pressure exists in the protecting hood 5. It the glass wall 17 off the hood 5 is broken or damaged, it then becomes possible tor the exhaust air to take another course, namely it fiows through the annular space 42 and ge of. the The annular space 4193' then air which is lowing out forwardly an annular cross-section which. envelops the lam 27, so that the outer air cannot gain access to the filament ot the in candescent lamp which. ma also have been destroyed. Owing to the air streaming out through the annular space 42 the pressure within the protecting hood 5 is reduced. The pressure of the exhaust air on the throttling disc 70 also ceases and the switch 57, 58, 59 is opened by the spring 56. The circult is thereby broken and the filament of the lamp extinguished. The extinguishfng of the filament occurs in every case while the filament is still enveloped by the annular currentstreaming out through the gap 42, whereby the ignition of the outer air, which. may be explosive, by the filament of the incandescent lamp is prevented with certainty. A. similar action takes place it the destruction oi the glass wall 17 of the protecting hood 5 takes place immediately after the turbine has been disconnected, that is to say, when the lamp 27 is still supplied with some current from the dynamo, owing to its not stopping immediately, and so still lights up weakly. So longas the circuit is not broken by the switch 57, 58, 59 suiiicient glass disc 17.

pressure exists in the protecting hood 5 to form at the annular space 42 a screen of exhaust air which protects the incand-sccnt lamp from the as -ess of the outer air. before this sore ining of the incandescent lamp ceases the circuit is broken by the circuit-brcakin switch and the filament of the lamp diluguished.

As may be seen, owing to the arrangement of the throttling disc 70 which controls the circuit breaking switch 57, 58, 59, it is possible to operate with a relatively low excess of pressure in the hood 5 whereby, on the one hand, the 'el'liciency or the compressed air motor 11 increased, and, on the other hand, the danger of the parts of the damaged glass disc .27 being blown Long 7 the controlling member for the switch a throttling disc for the emerging exhaustair,

on the one hand,.a relativelyhighpressure is exerted upon the throttling disc 70 when the glass disc is undamaged so that the bridge piece 59 and the contacts 57, 58 are firmly pressed together while, on the other hand, the controlling member or the switch is highly sensitive so that the switch is opened even when a'relatively small fallv in pressure occurs in the hood 5. This ensures with the that the lamp extinguished betore the screen of air which protects it disappears.

The invention is of course, not limited to the particular example illustrated but rea y alterations and other forms oi? construction are possible within the scope of the appended claims, without departing highest degree oi:- certainty from the spirit or sacrificing any of the ad 7 vantages of the invention.

1. A safety electric lamp comprising a having separate motor, generator and lamp chambers, an air inlet to the motor chamber, an air conducting passage between the motor and lamp chambers and a lateral final air outletin rear of the lamp chamber, a turbine in the motor chamber, a current generator in the generator chamber driven by said motor, a lamp in the lamp chamber supplied with current from the generator, a lens closing tlieztr ont, of the lamp chamber, a reflector partition subdividing the lamp chamber into front and rear compartments, with which rear compartment the air passage communicates, said partition being provided with an; air gap connectingthe two compartments and surrounding the lamp, a throttling device arranged in the .llllQ'OlE flow ot the a r from therear compartment to the final air outlet, and-a switch device controlling the supply of current to the lamp and governed'in acprovided with an air inlet, a front lamp 4 compartment provided witha lens/at the front thereof, an intermediate genera compartment, an air fiow passage between the motor compartment and the lampchamber, and a final exhaust outlet at one side of the, casing and in rear of the lamp chamher, a turbine motor in theinotorcompartment, an electric generator in the gene: ttor compartment, a lamp in the lamp compatment and supplied with current from said generator, a reflector partition subdividing the lampcompartment into frontand rear chambers with which rear chamber the air passage communicates, said partition he provided with annular gap cc.

ing said chambers and surrounding the lamp, a throttling disk arranged in the line of flow of the air from said rear chamber to the final exhaust outlet, a spring resisting movement of said disk in the throttling direction, and a circuit make and break switch governed by said disk and controlling the flow of current from the generator to the lamp.

3.. In an electrical safety lamp, a casing having a lamp chamber and an air exhaust outlet in communication With the rear portion of the lamp chamber, a glass wall closing the front of the lamp chamber, a genorator in the casing, an incandescent lamp in the lamp chamber and supplied with cur-,

rent from the generator, an air motor in the casing for driving the generator, the casing having a passage for conducting exhaust air from the motor to the rear portion oi the lamp casing, means controlled bypressure conditions in the lamp chamber" for governing the fioW of air from the lamp chamber to the air exhaust outlet and letting on or cutting oil the flow of current from the generator to the lamp, and a reflectorin the lamp chamber and surrounding the lamp and separating the lamp chamber into front and rear compartments, the former containing the lamp bulb and the latter communicating with the exhaust outlet and the air conductthe casing, an incandescent lamp in the lampv chamber and supplied with current from the generator, an air motor in the casing for driving the generator, the casing having a passage for conducting exhaust air from the motor to the rear portion of the lamp casing, means controlled by pressure conditions in the lamp chamber for governing the flow of air from the lamp chamber .to the air exhaust outlet and letting on or cutting, off the flow of current from the generator to the lamp, and a reflectorin the lampfchamber and surrounding thelamp and separating the lamp chamber into front and rear compartments, the former containing the lamp bulb and the latter ,communicatingwith the exhaust outlet and'the air conducting passage leading from the motor, said reflector comprising two sections having edge portions spaced to provide an annular air passage be,- tween said compartments and about the lamp bulb and adapted for the flow of a screening stream of air from the rear compartment to the front compartment and about the lamp bulb upon the fractureof said glassfront wall of the lamp chamber. I Y

5. In an electrical safety lamp, a casing having a lamp chamber and a lateral air exhaust outlet, a glass wall closing the front of the lamp chamber, a generator in the casing,

an incandescent lamp in the lamp chamber and supplied with current from the generator, a Wall at the rear of the lamp chamber and separating the same from the part of the casing containing the generator, said wall being provided with a lamp socket receiving the base of the lamp and with a ,re'cesshaving an annular groove therein communicating Wltl'l, the exhaust outlet, an air motor in the casing for driving the gener-' ator, the casing having a passage for conducting exhaust air from the motor to the rear portion of the lamp casing, a casing fitted in said recess in the rear wall of the lamp chamber and dividing the same into compartments in front and rear of said groove, the front compartment being in communication with the lamp chamber and having a lateral port communicating with the groove and air exhaust outlet, current supplying connections between the generator and lamp including contacts in the rear compartment of the recess, a switch in said rear compartment of the recess for coaction with said contacts, a throttling disk in the front compartment of the recess and controlling the flow of air from the lamp chamber through said port to the exhaust outlet, and a switch in therear compartment of the recess governed by variations ofpressure of the air upon the throttling disk for moving said switch into and out of engagement with the contacts. a

In testimony whereof I afiix my signature.

OTTO BECKER, JR; 

